Pollen Morphology Research Articles

Parrotia (Hamamelidaceae) pollen morphology and a glimpse into the fossil record and historical biogeography

The affiliation of fossil pollen grains of Hamamelidaceae with extant genera is still a challenge for palynologists, probably due to the scarcity of pollen morphological documentation and comparison of Hamamelidaceae genera and species and their fossil counterparts. Parrotia once had a much wider geographical range during geological time according to fossil records, including macrofossils (e.g., plant leaves, and flowers) and microfossils (e.g., pollen). However, assigning fossil pollen of Parrotia is yet difficult regardless of some previous work available on pollen morphology.In this study, we present new results after intensive re-examination on the pollen morphology of Parrotia using light microscope (LM) and scanning electron microscope (SEM), aiming to assess pollen diagnostic features as a guide for fossil pollen recognition. We also compared the reticulum sculptures and nanoscale ornamentations on the muri around lumina for six genera in the tribes Fothergilleae with the representative genera from the neighboring tribes Hamamelideae and Eustigmatea. Hamamelidaceae fossil pollen types from Miocene sediments in southeastern China were examined and identified. We found that 1) pollen grains of Parrotia persica and P. subaequalis have significantly different dimensions of the length of lumen and density of lumina (numbers/10 μm2) under SEM, and the lengths of polar axis, equatorial axis, colpus, bottom side of polar view and height of polar view under LM, respectively; 2) the peculiarities of reticulum, microechinae on the muri and arrangement pattern under SEM are useful diagnostic features to differentiate pollen types of Fothergilleae groups down to genus level from two neighboring tribes; 3) two sister species of Parrotia show identifiable characteristics of reticulum and microechinae based on high resolution imaging with SEM, however, it should be noted that assigning fossil pollen to Fothergilleae still need caution, because of some similar looking close genera under LM; 4) inter- and intraspecific pollen variations need to be carefully considered, when identifying dispersed or fossil pollen grains of Parrotia under low resolution of LM imaging; 5) nanoscale structures based on high resolution imaging for pollen surface sculptures are important keys to distinguishing different fossil pollen types of Hamamelidaceae, including Parrotia.Most of fossil sites of Parrotia are concentrated in Europe-Eurasia and Japan in East Asia, but there are relatively fewer in China and America. To have an insight into the historical biogeography of Parrotia, the global fossil records of Parrotia were comprehensively reviewed and visualized in three large regions (northern American, Europe-Eurasia and East Asia). The palaeophytogeography of Parrotia in light of fossil pollen in East Asia is also generally discussed. Further investigations of the fossil record of Parrotia are expected prior to fully picturing its past phytogeography and species diversity through time, particularly some missing links during Pliocene and Quaternary in China.

FTIR spectra from grass pollen: A quest for species-level resolution of Poaceae and Cerealia-type pollen grains

Palynological analysis based on spore and pollen morphology is well established in the field of palaeo-environmental reconstruction but is currently not fully exploited for understanding the history and development of cereal cultivation due to difficulties in visually differentiating between grass species (Poaceae). Here we employ a chemotaxonomic approach, by examining the chemical differences among Poaceae taxa, based on Fourier-transform infrared (FTIR) microspectroscopy data to overcome problems associated with morphological similarities across the Poaceae family. FTIR spectra of untreated and acetolysed pollen from 19 Poaceae taxa were used in our study. We used both populations and individual pollen grains to explore how we can minimise the effect of Mie scattering (spectral distortions caused by scattering of the incident IR beam) on spectra from individuals. Random forest classification algorithms were applied to explore our ability to differentiate taxa at the species level. We found that pollen grains treated with acetolysis yield better classification results (86% for individuals and 97% for populations) compared to untreated samples (65.7% for individuals and 83% for populations), since they are less affected by Mie scattering. The high classification success at species level on acetolysed individual pollen grains suggests that our chemotaxonomic method holds substantial promise in numerous areas of grass and in particular cereal pollen research, including elucidating the history of agriculture.

Calibration and measurement of micrometre-scale pollen particles for discrete element method parameters based on the Johnson-Kendal-Roberts model

Discrete element method (DEM) parameters are the basis for modelling the motion of particle systems. To verify the practicality of calibrating DEM simulation parameters for micrometre-sized pollen particles, spherical micrometre-sized tomato pollen was selected as the research object for a parameter calibration experiment. Constitutive parameters such as the pollen morphology, diameter, and density were obtained through experimental measurements. Then, the contact and collision process of pollen was measured and analysed using an atomic force microscope, and Young's modulus, surface energy, and recovery coefficient of pollen were calculated using the Johnson-Kendal-Roberts (JKR) contact model. A Plackett-Burman test was designed, and the significant factors were determined using the DEM simulation test for Young's modulus of pollen grains, pollen-pollen static friction coefficient, and the pollen-polypropylene static friction coefficient for the plastic floor. The parameter range was reduced using the steepest climbing test. A regression equation was determined according to the results of the Box-Behnken response surface analysis. When this equation was solved, Young's modulus of pollen grains was 5.25 × 106 Pa, the pollen-pollen static friction coefficient was 0.466, and the pollen-polypropylene plastic static friction coefficient was 0.417. From the accumulation verification experiment the relative error between measurement and the simulation was 1.01%, which indicates that a calibration experiment of micrometre-sized pollen particle parameters is feasible. Furthermore, the parameters obtained here can be used to calculate and predict the pollen pollination process.

Deep learning approaches to the phylogenetic placement of extinct pollen morphotypes.

The phylogenetic interpretation of pollen morphology is limited by our inability to recognize the evolutionary history embedded in pollen features. Deep learning offers tools for connecting morphology to phylogeny. Using neural networks, we developed an explicitly phylogenetic toolkit for analyzing the overall shape, internal structure, and texture of a pollen grain. Our analysis pipeline determines whether testing specimens are from known species based on uncertainty estimates. Features from specimens with uncertain taxonomy are passed to a multilayer perceptron network trained to transform these features into predicted phylogenetic distances from known taxa. We used these predicted distances to place specimens in a phylogeny using Bayesian inference. We trained and evaluated our models using optical superresolution micrographs of 30 extant Podocarpus species. We then used trained models to place nine fossil Podocarpidites specimens within the phylogeny. In doing so, we demonstrate that the phylogenetic history encoded in pollen morphology can be recognized by neural networks and that deep-learned features can be used in phylogenetic placement. Our approach makes extinction and speciation events that would otherwise be masked by the limited taxonomic resolution of the fossil pollen record visible to palynological analysis.

Astragalus roseocephalus, a new species of section Poliothrix from Pakistan

A new species, Astragalus roseocephalus sp. nov., is described and illustrated. It is known from Islamabad Capital Territory (Margalla hills), Rawalpindi district, Hazara and Kashmir. It belongs to Astragalus section Poliothrix Bunge. Morphologically, it is closely related to Astragalus leucocephalus Benth., but differs in height, presence of connate stipules, opposed to free lateral stipules in A. leucocephalus, stipule shape, leaf length, leaflet size, number, arrangement and shape, peduncle length, corolla colour, size and shape of standard, fruit shape and number of seeds. In addition, anatomy, pollen morphology, distribution and conservation status of the new species are discussed.

Micrometer insights into Nepeta genus: Pollen micromorphology unveiled

This study provides a comprehensive pollen micromorphology within the Nepeta genus, revealing intricate details about the pollen grains' structure and characteristics. The findings shed light on the evolutionary and taxonomical aspects of this plant genus, offering valuable insights for botanists and researchers studying Nepeta species. The pollen grains of 18 Nepeta species were studied using scanning electron microscopy (SEM) and light microscopy (LM) in Northern Pakistan. At the microscale, pollen quantitative measurements, qualitative traits, and diverse sculpturing patterns were reported and compared. Significant differences in pollen size, shape, ornamentation, and sculpturing patterns were discovered among the Nepeta species. Our data show that exine sculpturing is quite diverse, with most species exhibiting a reticulate perforate pollen pattern. Nepeta connata, Nepeta discolor, Nepeta elliptica, revealed a distinct bireticulate perforate exine stratification. Hexazonocolpate pollen is the most common. Furthermore, the surface membrane attributes of the colpus varied greatly, ranging from rough, scabrate, psilate, to sinuate patterns. Principal Component Analysis (PCA) was used to discover the key factors influencing pollen diversity. PCA results showed that polar and equatorial diameters, colpi size, and exine thickness were the most influential pollen features between Nepeta species. This study adds to our understanding of pollen morphology in the Nepeta genus, offering information on the vast range of characteristics found in this economically important group. The extensive characterization of pollen features provides useful insights for the categorization and differentiation of Nepeta species, adding to the Lamiaceae micromorphology.

Exploring the Impact of Metal-Based Nanofertilizers: A Case Study on Sunflower Pollen Morphology and Yield in Field Conditions

On a daily basis, a wide range of materials including inorganic nanoparticles (NPs) inadvertently find their way into the environment. Meanwhile, intentionally used NPs, such as the new generation of nanofertilizers (NFs) are designed to enhance agronomic production. However, their physicochemical properties and not-so-well understood effects raise potential risks to the plant reproductive cycle, specifically pollen development, a subject largely absent in academic research. Even slight contamination, deformation, or aberration of pollen could have enormous impacts on the ecosystem. Thus, our objective was to evaluate the influence of various metal-based NPs on sunflower pollen morphology and its yield. Nano-formulations were applied during the 2019–2021 agronomic seasons on two sunflower hybrids, Neostar and Edison, in Dolná Malanta, near Nitra, Slovak Republic. Pollen morphology findings indicated that conventional ZnSO4 had the most positive impact on the size of pollen grains compared to ZnO-NPs, Fe3O4-NPs, and the NP-free control. Gold-NPs on SiO2 mesoporous silica (AuSi-NPs) showed a statistically insignificant impact, while the use of TiO2-NPs in agriculture remained a topic of debate. Surprisingly, pollen characteristics did not fully correspond to crop yields. Despite causing a reduction in pollen grain size, the TiO2-NPs consistently showed the highest yield compared to other variants. Employing low concentrations of NFs did not notably alter pollen morphology, reinforcing our commitment to eco-friendly, precise, and sustainable agriculture.

Pollen morphology and its taxonomic potential in Stachytarpheta sect. Stachytarpheta (Verbenaceae) occurring in Brazil

Verbenaceae is an important element of Neotropical flora, and Stachytarpheta is the second largest genus in the family. Whereas pollen morphology has helped in the differentiation of several taxonomic groups, palynological data on Stachytarpheta are still scarce, especially for Brazil, where its greatest species richness is concentrated. The present work aimed to analyze the pollen morphology of selected species of Stachytarpheta sect. Stachytarpheta, to aid in the taxonomy of the group. Pollen grains from 11 species were analyzed before and after chemical treatment, measured and treated statistically; multivariate analyses were also performed. The pollen grains of S. sect. Stachytarpheta are large or very large monads, that are radially symmetric and isopolar, with amb varying among triangular, subtriangular, subcircular, and quadrangular, and shape among subspheroidal, oblate-spheroidal, prolate-spheroidal, and subprolate. The three or four apertures are of the colpus type and narrow. The ornamentation is verrucate, with perforations at the base of the verrucae and isolated granules. The pollen grains also possess a margin and an anapertural membrane, which are the main characteristics useful for differentiating the species of the section. The size, amb, shape, apertural type, and ornamentation are also important for morphological differentiation, but multivariate analyses did not support the groups formed based on pollen characterization. An identification key is provided to distinguish the 11 studied species based on pollen morphology.

A taxonomic revision of Thai Fernandoa Welw. ex Seem. (Bignoniaceae).

A taxonomic revision of Fernandoa Welw. ex Seem. (Bignoniaceae) in Thailand is presented. Two species, F.adenophylla (Wall. ex G. Don) Steenis and F.collignonii (Dop) Steenis, are enumerated with updated morphological descriptions, illustrations and a taxonomic identification key, together with notes on distributions, distribution maps, habitats and ecology, phenology, conservation assessments, etymology, vernacular names, uses, and specimens examined. The collection of Wallich Cat. 6502A from Myanmar, Ava at G [G00133642] is designated here as the lectotype of F.adenophylla in a second step lectotypification. F.collignonii has a conservation status of Endangered [EN]. The leaf, stem, and wood anatomy and pollen morphology of F.adenophylla are also reported in this study.

Examining the Effects of Prunus Necrotic Ringspot Virus (PNRSV) and Prune Dwarf Virus (PDV) on Peach (Prunus persica) Pollen Health

Pollen health is a key determinant of successful plant reproduction and crop yield. Prunus necrotic ringspot virus (PNRSV) and prune dwarf virus (PDV) are pollen-borne viruses of stone fruits, including peaches, primarily transmitted through vegetative propagation (i.e., grafting) and pollen. Here, we investigated the effects of PNRSV and PDV infection on peach pollen morphology, viability, and germination. Our scanning electron microscopy on pollen morphology, as well as pollen viability and germination assays, showed that PNRSV has cultivar-specific effects on pollen health; compared with pollen from virus-negative trees, PNRSV infection resulted in distorted shape, reduced viability, and germination of pollen grains of peach cultivar Red Top, but no significant effects on viability or germination were detected on cultivar Zee Lady pollen grains. PDV infection affected pollen width and reduced pollen viability but did not affect pollen germination when compared between PDV-positive and PDV-negative pollen grains. We discuss our results in terms of potential evolutionary consequences and implications on virus epidemiology and disease management in orchards. Investigating the effects of viral infection on pollen health will ultimately enhance our understanding of the transmission of pollen-borne viruses. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Comprehensive study of allergenic tree species: Palynological insights enhanced by HPLC and GC-MS profiling.

Considering the limited data available on tree species in Uzbekistan, this research aimed to provide new insights. We gathered plant samples from different locations within Samarkand city and thoughtfully selected 15 tree species that represent the country's flora. Using scanning electron microscopy, we conducted comprehensive analyses of pollen morphology, revealing a diverse range of variations in the shapes, dimensions, and surface characteristics displayed by pollen grains. Distinct ornamentations such as micro-echinate, reticulate, rugulate, gemmate-verrucate, and verrucate-scabrate patterns facilitated the differentiation of species. These scanning electron microscopy findings enhance our comprehension of tree species diversity, adaptation, and ecological roles. In addition, leaf extracts were analyzed using HPLC and GC-MS, revealing a plethora of bioactive compounds, including catechins, chlorogenic acid, vanillic acid, and others. Furthermore, GC-MS analysis revealed the presence of seven key compounds, including 1-hexadecyne, 2-chloroethanol, 1,6-heptadiene, 2-methyl-, 5-bromoadamantan-2-one, ethyl 3-(3-pyridyl) propenoate, bis (2-ethylhexyl) phthalate, and quercetin. This study demonstrates the effectiveness of this method in assessing the quality of leaf extracts from tree species by examining both microscopic characteristics and chemical composition. This multifaceted approach has deepened our understanding of the characteristics and chemical compositions of these trees, thus contributing to a more profound appreciation of their ecological significance and potential applications.

Pollen morphology of Clerodendrum L. (Lamiaceae) from China and its systematic implications.

Pollen morphology of 26 taxa of Clerodendrum, as well as one species of Volkameria from China, was investigated through a scanning electron microscope (SEM). Pollen grains of Clerodendrum are monads, radiosymmetric and tricolpate, with medium or large size. The equatorial view of the pollen grains is spheroidal or subprolate and the polar view is (sub) circular or rounded triangular. The colpus membrane of the investigated taxa is sunken (rarely even). Five varying pollen types are delimited on the basis of exine sculpturing: (1) spine-tectum perforatum; (2) spine-tectum imperforatum; (3) microspine-tectum perforatum; (4) microspine-tectum imperforatum; and (5) obtuser spine. The results indicate that Clerodendrum is closely related to several genera in Lamiaceae, including Aegiphila, Amasonia, Kalaharia, Tetraclea, Volkameria, Oxera, Faradaya, and Hosea, as supported by previous phylogenic studies. Additionally, the conventional infrageneric classification of Clerodendrum based on inflorescence and leaf characters is not supported by the results. However, the palynological data can be used to identify some closely related species with similar external characteristics. In conclusion, the investigation of pollen morphology not only contributes novel data from palynology for Clerodendrum but also provides a basis for future comprehensive classification of this genus.

Evolution of pollen grain morphology in Amorimia and allies evidences the importance of palynological apomorphies and homoplasies in Malpighiaceae systematics

Background and aims – Pollen grain morphology is an important morphological character for aiding the systematics of flowering plants. For Malpighiaceae, only a single unpublished palynological study has comprehensively sampled ca 60 of this family’s 75 currently accepted genera. To test the systematic relevance of pollen morphology in Amorimia and allies, we characterised the pollen morphology of these lineages. We scored, coded, and mapped 12 characters onto the most recent molecular phylogeny of Amorimia and allies. Material and methods – We sampled 13 species of Amorimia as ingroup and two species of Mascagnia and Ectopopterys soejartoi as outgroup. Pollen grains were acetolised, characterised, and measured using light microscopy and scanning electron microscopy. Pollen quantitative measurements were submitted to a PCA multivariate analysis. Additionally, quantitative and qualitative characters were scored and coded into 12 characters and mapped onto the molecular phylogeny of Amorimia and allies. Key results – Amorimia and allies are stenopalynous due to all species showing the same pollen type, with some subtle differences between the pollen grains, such as details of ornamentation, shape, size, and thickness of the pollen exine. However, the patterns of pollen grain evolution showed that few qualitative and apomorphic characters are informative for intrageneric distinction (i.e. type and number of apertures), and almost all quantitative and homoplastic characters analysed were informative at infrageneric levels within Malpighiaceae. Conclusion – Our results demonstrate that even though the pollen morphology characters of Amorimia and allies show subtle variation, both qualitative and quantitative apomorphic and/or homoplastic characters are highly informative for intra- and infrageneric levels in Malpighiaceae when analysed in a phylogenetic context.

Comparison of pollen characters in Lysiostyles Benth. and allied genera (tribe Maripeae – Convolvulaceae)

Pollen morphology and ultrastructure was studied for the monotypic genus Lysiostyles (Convolvulaceae, tribe Maripeae) distributed in Guyana, Suriname and Venezuela. Lysiostyles scandens is a liana with alternate leaves, thyrsiform inflorescence, white corolla with acuminate lobes, five epipetalous stamens, anthers with elongated connectives and a superior ovary with two carpels. The styles are glabrous, branched and divided at the base with cylindrical stigma and lignified and indehiscent fruits. Pollen was collected from specimens in the herbaria RB, L, and U. For observation under light microscopy (LM) and scanning electron microscopy (SEM), pollen grains were prepared using acetolysis. Non-acetolysed pollen grains were prepared for observation by transmission electron microscopy (TEM). Pollen is small to medium sized, isopolar, mostly subprolate, and subcircular amb, tricolpate and tectate with a wavy relief and microechinate tectum. The sexine is thicker than the nexine. The pollen features observed in Lysiostyles are important for the characterisation of the genus, as well as for understanding relationships within the tribe Maripeae (Dicranostyles and Maripa), and support patterns suggested by phylogenetic studies.

PALYNOLOGICAL DIVERSITY OF POLLEN MORPHOLOGY IN ENDEMIC NORTHERN IRAQI HYPERICUM SPECIES (HYPERICACEAE)

The presented research investigated the pollen morphology of endemic Iraqi Hypericum species. The study revealed phenotypic features of pollen grains in the polar and equatorial views and their quantitative and qualitative characteristics. The results showed that the pollen grains of the genus Hypericum were radially symmetrical and isopolar, and their apertures were simple and tricolporate, except the species H. davisii, distinguished as tetracolprate. Dividing the studied species based on pollen grain sizes comprised two groups. Small pollen grains with an average length of the equatorial view ranged between 10–16 μm in H. lysimachioides and H. vermiculare. Medium-sized pollen grains with an average extent between 17–26 μm emerged in the species, i.e., H. retusum, H. triquetrifolium, H. perforatum, H. lydium, H. tetrapterum, H. asperulium, H. scabrum, and H. davisii. Pollen grains, also divided according to the P/E ratio, had two main groups. The pollen grains were subprolate and spherical, with the exine sculpturing examined by a scanning electron microscope (SEM), and isolated into four groups: 1) microreticulate reticulum, including H. asperulium, H. lydium, and H. vermiculare, 2) perforate, i.e., H. retusum, H. scabrum, H. tetrapterum, and H. triquetrifolium, 3) psilate with H. perforatum and H. davisii, 4) and reticulate exine sculpturing in H. lysimachioides, all isolated from the rest of the species. SEM images showed the thickness of exine ranged from 0.5 to 2 μm. The topical study also added H. davisii as a new species with no previous records in Iraq. This pollen study added valuable data for taxonomy and suggested that it should proceed with its first-time registration in Iraq. The pertinent research could provide a taxonomical key for Hypericum species in Iraq.

A study of pollen morphology for some plants species in Al-Hada area in Taif province

A study of pollen morphology for some plants species in Al-Hada area in Taif province

Pollen variability in Quercus L. species and relative systematic implications

This study aims to address one of the challenges related to the complexity of the Quercus L. genus, that is the identification of structural elements favouring the systematic identification of the oak pollen. Thus, in this contribution, we explored the variation of morphometric and chemical parameters in pollen samples collected from 47 different Quercus species and hybrids. Several qualitative (e.g., outline in polar view, class, aperture structures) and quantitative (e.g., diameter, exine and sporoderm thickness, autofluorescence, content in proteins and plant metabolites) features were evaluated by optic microscopy and spectrophotometric assays. Statistical analyses were also carried out to assess significant correlations and clustering effects among the studied taxa, based on phenotypical and biochemical data, to identify the parameters which could be useful for taxonomic discrimination at inter- and intra-specific level. Only few morphological traits showed the potentiality to be diagnostic, such as pollen diameter and outline in polar view. The intensity of pollen autofluorescence varied among the samples but it did not seem to correlate with protein, carotenoid, phenolic and flavonoid content. However, differences in protein and carotenoid levels were detected, suggesting them as possible taxonomic discriminants for oak pollen. Thus, our work represents a step forward in understanding morphology and biochemistry of oak pollen, constitutes an experimental set-up applicable in future systematic studies on other genera, and opens new perspectives for further molecular investigations on Quercus species.

A “hairy situation” in Minas Gerais, Brazil: a striking new species of Krenakanthus (Bromeliaceae: Bromelioideae) covered with uniseriate trichomes

A new species of Krenakanthus, a member of the bromelioid “Cryptanthoid complex”, is described based on plants discovered through collaborative citizen science. Krenakanthus ribeiranus and its only congener K. roseolilacinus are endemic to the “João Pinto Center of Biodiversity”, a still poorly explored region with Campos Rupestres and associated vegetation in the Rio Doce Valley, in eastern Minas Gerais state, Brazil. The unusual combination of morphological characters of K. ribeiranus, highlighted by plant delicacy and almost all leaf and flower parts covered by uniseriate, hair-like trichomes, is illustrated and discussed in comparison with K. roseolilacinus, including leaf and seed anatomy, as well as pollen morphology. This micro-endemic species is assessed as Critically Endangered, reinforcing the need for strategy to protect the biodiversity of the region. The morphology of the new species validates and strengthens the diagnostic flower characters used in the circumscription of Krenakanthus, suggesting as secondary diagnostic characters the habit, stature, and leaf conformation.

Pollen morphology of Matthiola and the related genus Dvorakia (Brassicaceae) in Iran

Our study focused on the pollen morphology of 13 species of Matthiola and the closely related genus Dvorakia. We used light and scanning electron microscopes to examine the importance of pollen characteristics in classifying these genera. Pollen grains were acetolysed, measured, photographed, and described based on qualitative and quantitative characteristics. Here, we present statistical analyses and multivariate statistics for quantitative data. Pollen in both genera are tricolpate and varies in shape from subprolate to prolate. We distinguish two pollen types based on lumen width. Matthiola pollen has both reticulate and macroreticulate ornamentation, while Dvorakia alyssifolia pollen is reticulate. The thickness of the exine and the width of the mesocolpium are important traits in addition to exine ornamentation. Iranian Dvorakia and Matthiola species’ pollen size can be divided into four types, one of which is Type I (Dvorakia alyssifolia type). Among the examined species, M. tomentosa has the smallest pollen grains, while D. alyssifolia has the largest grains. Pollen morphology confirms the transfer of D. alyssifolia from Matthiola to Dvorakia. Additionally, we propose a species key for the genera.

Pollen morphology for successful pollination dependent on pollinator taxa in a generalist plant: relationship with foraging behavior.

Pollen morphology varies at inter- and intraspecific levels. Its interaction with pollinator behavior and morphology determines the probability of successful pollination. We tested whether pollen morphology promoting successful pollination differs depending on pollinator taxa in a generalist shrub, Weigela hortensis (Caprifoliaceae). We identified flower visitors carrying pollen from anthers to stigmas and compared the spine length and diameter of the pollen grains they carried. We found that pollen on the bodies of bumble bees and hunch-back flies and the scopae of small bees (including andrenid bees) contributed to seed production. Pollen grains on the bodies of bumble bees had longer spines than those on the scopae of andrenid bees or the bodies of hunch-back flies. Pollen grains on the bodies of bumble bees and the scopae of andrenid bees had larger diameters than those on hunch-back flies. Bumble bees collected pollen grains with shorter spines and larger diameters on their corbiculae while andrenid bees collected pollen grains with shorter spines and intermediate diameters on their scopae. The differences in morphology of pollen carried by pollinators reflected the tendency of bees to collect pollen with specific morphology into corbiculae/scopae. Our findings suggest that pollen morphology has diversified to facilitate successful pollination by pollinating partners.